Newsround Online caught up with him to see what the pompous Mr Weasley thinks about Prisoner of Azkaban

Are you looking forward to POA coming out?
I am really looking forward to the POA coming out. From what I have seen it looks really really good. It should be really promising.

What do you think the fans will think of it?
I think the fans will be impressed to be honest, obviously the response to the first two films was overwhelmingly good. This film is different but I think this is the right progression for the films. I think it is going to go down well.

How is this film different?
The book itself is a lot more grown up and dark and more sinister than the first two. In the first two there is a lot of getting to know the characters and the whole background to Potter.

The third one is really sinister and threatening. Alfonso has really shown the way the different characters develop. From the bits I have seen, it is more threatening and foreboding.

How is Alfonso different to Chris Columbus?
Alfonso is great. He's worked on some of my favourite films of all time, like Great Expectations and Y tu Mama Tambien (a Mexican film). I have been a fan of his for a very long time. When he heard he was going to be the director I couldn't believe it.

Like everybody else, I thought: 'Hang on a minute - this is a bit of a left turn at the traffic lights for him. He's going on to make POA.' But the way he works really suits the storyline. He does it down to a T.

It's a good way to move on from Chris Columbus directing - he was fantastic too. And he's still working on the films. But it's good to have a new director and it keeps the films fresh. Every new person adds a different dimension to it.

What's your fave scene in POA?
When people used to ask me that question I always used to say the scene on the stair case when the Fat Lady's portrait is slashed open by Sirius Black. I really did enjoy doing that one.

But I was watching it online the other day, and there's 10 minutes of behind-the-scenes footage on the internet and I saw a scene I'd forgotten I had filmed!

It's where Sirius Black comes into the Gryffindor dormitory and wakes up Ron in bed and he's screaming. It was quite fun as I was lying there looked annoyed. We spent all day filming in our pyjamas, it was fun. It was a slightly different scene, a bit more wacky, more comedy.

What is it like working with some of the older actors like Gary Oldman, who plays Sirius?
I've never actually met Gary Oldman! My scenes didn't really correspond with him. But meeting some of these actors over the last 4 years - actors like Alan Rickman, Maggie Smith and everyone else, has been incredible, people like Michael Gambon, who is absolutely amazing, he's one of our greatest actors.

That's the great thing about doing Potter - you are guaranteed to be working with some of the best people in the industry ever. You can learn so much from them. Just from standing there watching people like Michael Gambon. He is really stunning.

What are you doing now?
Since November I've been doing bits and pieces. Potter automatically takes over much of my time. It's all running up to the Azkaban premiere at the moment. I'm also due to start filming on the Goblet of Fire soon. It is all starting to take form now. It's my next big thing.

I am also running my own professional theatre company now. I set it up in January with a director friend of mine. I am getting that on the road. We did a production in Norfolk in January which went well.

Will you be at the UK premiere?
Yes. I have not seen it all the way through yet. I will go to a cast and crew screening the day before the premiere. I've done some post-production work, like voice work, so I have seen about half an hour of the film. It looks pretty damn good.

What's it like working with the animals on Potter, like Crookshanks?
Crookshanks is fantastic, his real name is Crackerjack. I love that cat, he's got a flat face and looks like he's run into a wall.

I haven't had so much luck with animals on the Potter set though. I had trouble with Neville's toad on the first film. There's was a bit where we're in the Gryffindor corridor and I'm showing the new pupils around.

I ask: 'Has anyone got any questions?' and Neville raises his hand and said: 'Have you seen my toad?' I had it in my pocket so it was there on and off for 3 days while we were filming, but it kept weeing on me! Everyone kept laughing at me.

How are the rest of the Weasley clan?
They're all good. I haven't seen them for a while. I finished filming on POA before Christmas. I did see Bonnie in March though. They all seem well, we keep in touch. We spend so much time together for most of the year on set. We're all still one big happy family!